Alliaria petiolata (M. Bieb.) Cavara & Grande (Brassicaceae) is an invasive species which is native in Europe and SW Asia. This species is currently invading the understory of mature temperate forests of North America. In Korea, A. petiolata is found to invade and colonize areas at forest margins along roadsides (Samcheok-si, Gangwon-do). This initial investigation serves to inform of the importance of early detection and extermination of this particular weed in Korea.